In an engine dynamometer system and/or a chassis dynamometer system, which carry a rocking type dynamometer, a load cell is used as a sensor for detecting torque for the control and measurement of the system. The load cell detects torque acting on a rocking piece of the dynamometer, through a torque arm extending from the rocking piece (see Patent Document 1). In such a structure, in addition to torque which should be actually detected by the dynamometer, a torque fluctuation component is superimposed on an output signal from the load cell, due to natural vibration of the rocking piece; and this fluctuation component is fundamentally unnecessary for the control and measurement of the system. Accordingly, there has been conventionally proposed a technique for eliminating an unnecessary torque fluctuation component from an output signal from a load cell (see Patent Documents 1 and 2).
In the technique as disclosed in Patent Documents 1 and 2, an acceleration′ sensor is provided to a rocking piece and a torque arm, separately from a load cell; and an output signal from the acceleration sensor and an output signal from the load cell are composited through predetermined procedures, thereby eliminating fluctuation due to natural vibration of the rocking piece from the output signal from the load cell.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2006-184135
Patent Document 2: Japanese Unexamined Patent Application, Publication No. S58-90135
Patent Document 3: Japanese Unexamined Patent Application, Publication No. H1-138836